We are specifically referring to Indian Runners.
After much study regarding weight loss it seems that 14% over the development of the duckling in the egg is optimal.
Our eggs were weighed upon setting in the incubator.
It is was a standard Brinsea auto turning, still air incubator that has the addition of a digital thermometer/hygrometer and two small fans taken from a computer power supply to circulate the air in the unit. ( so, effectively it is not a still air unit anymore..... )
We also play classical music to the eggs 24/7

Temperature at between 37.2F and 37.6F
Humidity around 50-55%
The average egg weighed roughly 60 grams
After the first 50 hours weighed again.
for sure something is happening...
The average loss is 1.25 grams! ( over 50 hours )
Now.... If average loss over the whole incubation period is 14% the total loss should be around 8.4 grams.
I know porosity, shell thickness, humidity and temperature are all factors in is...
My question is.....
It seems that 1.25 grams in the first 50 hours seems to be a massive loss.
Does anyone know if this weight loss is linear? or is there a larger loss at the beginning of gestation and it tails off as the embryo metabolises the yolk and the airsac size increases?
Atleast something is happening!!!

I am wondering if an unfertilized ( control ) egg placed in the enviroment ( and monitored very carefully ) would lose weight at all or at a similar rate to a fertilised gestating egg.
Any answers?
Ta!